Tips for practicing in secret
A lot of us, for reasons, have to practice in secret. Whether it's because you're staying with your parents or because you share a dorm room, here are some tricks that I myself use:
Honestly everything comes down to how good you can lie or act. If you're able to, convince your family that you're just very interested in Greek mythology and that's it. Percy Jackson, Epic the Musical, the Illiad and Odyssey, anything that you can watch or read related to the Greek gods will help you sell it as "no I just really like Greek mythology". And once you sell it like that you can get a bunch of statues and be like "no it's just because I really like mythology 🥺".
This general tactic works well with anything, slowly introduce the idea of you like essential oils or incense and frame it as just liking smells or something.
But more specifically, here are some ideas for alters and shrines:
On your bedside table: everyone keeps random clutter on their bedside table so it's the perfect place, no one will think anything of it if there's "random" candles or trinkets lying on it.
In a drawer: you don't have to keep everything in the same place, it's ok to lights incense somewhere else because you don't want to start a fire.
On top of a dresser: this is another one where people leave random clutter all the time so no one will think anything of it if there's "random" dishes or something
Outside: for libations which you pour into the ground, you can just find a spot behind your house or even a specific spot at a park.
Tea: this is one of my favorites because there are so many types of tea that you can prepare for different gods, and no one will think anything if you leave a cup of tea sitting for a bit
Milk: same with the tea, really you just need to sell yourself as having a bad memory lately. Depends on how strict the place you're in is though
Frankincense: if you live in a religious house this is perfect, frankincense was a gift from the wise men. It also was a very common offering in ancient Greece. This one doesn't work if you're in a dorm or apartment that doesn't allow smoke, however you can always just bring it outside and wait for it to go out in it's own depending on the weather and how much time you have
Anything smelly like perfumes and essential oils can be used as an offering really
If you have a jar that isn't see-through that is also a great way to get away with offerings. Maybe a clay container with a lid or something.
Honestly you really just need to get creative with it. Think about what foods you can leave out and frame it as an accident. Think about what smells you can have that wouldn't make people suspicious.